1. Field of the Invention
The present invention is directed to a regulator for regulating the flow of ink from an ink source to a print head in a printer; and, more particularly, to a regulator that is relatively independent upon the inlet pressure, such that the functionality of the regulator is relatively independent of the inlet pressure of the ink source.
2. Background of the Invention
The flow of fluids through predetermined conduits has been generally been accomplished using a valve and/or a pressure source. More specifically, valves come in various shapes and sizes and include as a subset, check valves. These valves prevent the reversal of fluid flow from the direction the fluid passed by the valve. A limitation of check valves is that the volumetric flow of the fluid past the valve is controlled by the inlet side fluid pressure. If the inlet pressure is greater than the outlet pressure, the valve will open and fluid will pass by the valve; if not, the inlet fluid will be relatively stagnant and the valve will not open.
Inkjet printers must take ink from an ink source and direct the ink to the print head where the ink is selectively deposited onto a substrate to form dots comprising an image discemable by the human eye. Two general types of systems have been developed for providing the pressure source to facilitate movement of the ink from the ink source to the print head. These generally include gravitational flow system and pumping systems. Pumping systems as the title would imply create an artificial pressure differential between the ink source and the print head to pump the fluid from the ink source to the print head. Generally, these pumping systems have many moving parts and need complex flow control system operatively coupled thereto. Gravitational flow avoids many of these moving parts and complex systems.
Gravitational fluid flow is the most common way of delivering ink from an ink reservoir to a print head for eventual deposition onto a substrate, especially when the print head includes a carrier for the ink source. However, this gravitational flow may cause a problem in that excess ink is allowed to enter the print head and accumulate, being thereafter released or deposited onto an unintended substrate or onto one or more components of the inkjet printer. Thus, the issue of selective control of ink flow from a gravitational source has also relied upon the use of valves. As discussed above, a check valve has not unitarily been able to solve the problems of regulating ink flow, at least in part because the inlet pressure varies with atmospheric pressure, and when the valve is submerged, the pressure exerted by the fluid itself.
U.S. Pat. No. 6,422,693, entitled xe2x80x9cInk Interconnect Between Print Cartridge and Carriagexe2x80x9d, assigned to Hewlett-Packard Company, describes an internal regulator for a print cartridge that regulates the pressure of the ink chamber within the print cartridge. The regulator design includes a plurality of moving parts having many complex features. Thus, there is a need for a regulator to regulate the flow of ink from an ink source to a print head that includes fewer moving parts, that is relatively easy to manufacture and assemble, and that does not necessitate direct coupling to the atmosphere to properly function.
The invention is directed to a mechanical device providing control over the flow of a fluid from a fluid source to at least a point of accumulation. More specifically, the invention is directed to an ink flow regulator that selectively allows fluid communication between the ink source and the print head so as to supply the print head with ink, while substantially inhibiting the free flow through of print head. The invention comprises a pressurized chamber, generally exhibiting negative gauge pressure therewithin, having an ink flow inlet and an ink flow outlet. A seal is biased against the ink inlet to allow selective fluid communication between the interior of the pressurized chamber and an ink source. A flexible wall, acting as a diaphragm, is integrated with a chamber wall to selectively expand outwardly from and contract inwardly towards the interior of the chamber depending upon the relative pressure differential across the flexible wall. The pressure differential depends upon the pressure of the interior of the chamber verses the pressure on the outside of the flexible wall.
As the flexible wall contracts inwardly towards the interior of the chamber, it actuates a lever. The lever includes a sealing arm and an opposing flexible arm, and pivots on a fulcrum. The sealing arm includes the seal biased against the ink inlet, while the flexible arm is angled with respect to the sealing arm and includes a spoon-shaped aspect contacting the flexible wall. As the flexible wall continues contracting inward, the flexible arm flexes without pivoting the lever until the force of the wall against the flexible arm is sufficient to overcome the bias biasing the sealing arm against the inlet. When the force against the lever is sufficient to overcome the bias, the lever pivots about the fulcrum to release the seal at the ink inlet, thereby allowing ink to flow into the chamber until the pressure differential is reduced such that the bias again overcomes the reduced push created by the inward contraction of the flexible wall.
It is noted that the invention is not a check valve, as the operation of the regulator is independent from the inlet pressure. In other words, a check valve is dependent upon the inlet pressure, whereas this system of the present invention provides a relatively small inlet cross sectional area in relation to the size and relative forces action upon the regulator system that effectively negates any variance in inlet pressure. Thus, increasing the inlet pressure does not affect the operation of the regulator.
It is a first aspect of the present invention to provide a regulator adapted to regulate the throughput of an ink between an ink source and a print head, the regulator comprising: (a) a pressurized chamber including an ink inlet in fluid communication with the ink source, an ink outlet in fluid communication with the print head, and at least one flexible wall; and, (b) a lever including a flexible arm extending along a portion of the flexible wall and an opposing arm operatively coupled to a seal biased to close the ink inlet when the lever is in a first position and to open the ink inlet to allow fluid communication between the ink inlet and the pressurized chamber when the lever is pivoted to a second position; where a lower pressure differential across the flexible wall causes the flexible wall to actuate the flexible arm, pivoting the lever to the first position (inlet closed), where a higher pressure differential across the flexible wall causes the flexible wall to actuate the flexible arm to pivot the lever to the second position (inlet open), and where a pressure change from the lower pressure differential to the higher pressure differential across the flexible wall causes the flexible wall to actuate and flex the flexible arm without causing the lever to pivot.
In a more detailed embodiment of the first aspect, the lever includes a fulcrum positioned in-between the seal and the flexible arm. In another more detailed embodiment, the lever is located at least partly within the pressurized chamber. In yet another more detailed embodiment, the exterior flexible wall directly contacts the flexible arm. In a further detailed embodiment, the exterior flexible wall comprises a polymer film. In still a further more detailed embodiment, the exterior flexible wall is operatively mounted to the exterior of the pressurized chamber over a hole extending through a wall of the pressurized chamber. In yet a further more detailed embodiment, the pressurized chamber comprises a cap and a body. In another detailed embodiment, the ink inlet and the ink outlet spatially oppose one another. In yet another more detailed embodiment, an exterior surface of the exterior flexible wall is exposed to a fluid having a substantially constant pressure. In still a further more detailed embodiment, the lever includes a bearing pin, and the pressurized chamber includes a seat adapted to receive the bearing pin of the lever.
It is a second aspect of the present invention to provide a fluid regulator adapted to regulate the throughput of an ink between an ink source and a print head, the regulator comprising: (a) a pressurized chamber including an ink inlet in fluid communication with an ink source, an ink outlet in fluid communication with a print head, and at least one flexible wall; and, (b) a valve biased to restrict fluid communication between the ink source and the pressurized chamber, where the flexible wall actuates the valve to overcome the bias in response to a predetermined pressure differential across the flexible wall to provide fluid communication between the ink source and the pressurized chamber, where the fluid communication between the pressurized chamber and the ink source decreases the pressure differential across the flexible wall, and where the valve restricts fluid communication between the ink source and the pressurized chamber when the pressure differential across the flexible wall is less than the predetermined pressure differential.
In a more detailed embodiment of the second aspect, the valve includes a pivotable lever having an ink inlet seal operatively coupled to a first arm of the lever. In another more detailed embodiment, the pivotable lever is biased in a first direction, positioning the seal to restrict fluid communication between the ink source and the pressurized chamber, and the exterior flexible wall actuates the pivotable lever to a second direction to overcome the bias in response to a predetermined pressure differential across the exterior flexible wall, repositioning the seal to provide fluid communication between the ink source and the pressurized chamber. In yet another more detailed embodiment, a fulcrum of the lever is positioned in-between the seal and the flexible arm. In a more detailed embodiment, the exterior flexible wall directly actuates the pivotable lever. In a further detailed embodiment, the exterior flexible wall comprises a polymer film. In still a further more detailed embodiment, the exterior flexible wall is operatively mounted to the exterior of the pressurized chamber over a hole extending through a wall of the pressurized chamber. In yet a further more detailed embodiment, the pressurized chamber comprises at least two components.
It is a third aspect of the present invention to provide a print cartridge comprising: (a) an ink reservoir containing an ink supply, (b) a print head; and, (c) a regulator for regulating the flow of ink between the ink supply and the print head, where the regulator includes: (i) a pressurized chamber having an ink inlet in fluid communication with the ink supply and an ink outlet in fluid communication with the print head; (ii) an inlet seal positionable between a closed position closing the ink inlet and an open position opening the ink inlet; (iii) a bias biasing the inlet seal to the closed position; and, (iv) a pressure actuator adapted to overcome the bias and position the inlet seal to the open position when pressure differential between pressure within the pressurized chamber versus pressure outside the pressurized chamber increases to a predetermined level.
In a more detailed embodiment of the third aspect, the pressure actuator includes a lever having a first arm and an opposing second arm, the first arm being operatively coupled to the inlet seal and the second arm being operatively coupled to the diaphragm, the lever being pivotable between a first position in which the inlet seal is in the closed position and a second position in which the inlet seal is in the open position. In a further detailed embodiment, the diaphragm contracts inwardly with respect to the pressurized chamber as the pressure differential increases. In yet a further detailed embodiment, the second arm of the lever is a flexible arm. In a more detailed embodiment, the regulator is positioned within the ink reservoir such that the outer surface of the diaphragm is exposed to the interior of the ink reservoir. In another more detailed embodiment, a plurality of ink reservoirs and a respective plurality of regulators are positioned within the print cartridge.
It is a fourth aspect of the present invention to provide a method of regulating the throughput of ink from an ink source to an inkjet print head. The method includes the step of automatically actuating a valve in response to a higher pressure differential across a membrane, which separates a pressurized ink chamber and an area surrounding the pressurized chamber, where such actuation is operative at the higher pressure differential to open the valve allowing fluid communication between the ink source and the pressurized ink chamber thereby causing a subsequent decrease the pressure differential across the membrane, and operative at a resulting lower pressure differential to close the valve again so as to inhibit again fluid communication between the ink source and the ink chamber.
In a more detailed embodiment of the fourth aspect, the valve comprises a lever operatively coupled to a seal that selectively restricts fluid communication between the pressurized ink chamber and the ink source. In another more detailed embodiment, an area surrounding the pressurized chamber includes an ink reservoir that is also the ink source.
It is a fifth aspect of the present invention to provide a method of regulating the throughput of ink from an ink source to an inkjet print head. The method includes the steps of: separating a first body of ink from a second body of ink utilizing at least in part a flexible membrane; deforming the flexible membrane in response to a pressure differential between the first body of ink and second body of ink; and, opening a valve in response to the deformation of the membrane, wherein opening of the valve facilitates fluid communication between the first body of ink and the second body of ink and decreases the deformation of the membrane, thereby closing the valve.
In a more detailed embodiment of the fifth aspect, the step of opening a valve includes the step of actuating a lever operatively coupled between the valve and the flexible barrier. In a further detailed embodiment, the lever is biased to close the valve.
It is a sixth aspect of the present invention to provide an ink cartridge comprising: (a) a plurality of individual ink reservoirs maintained to inhibit commingling of the respective inks within the plurality of individual reservoirs, while at least two of the plurality of individual ink reservoirs share a common wall; and, (b) a plurality of ink regulators adapted to regulate the throughput of an ink within each of the plurality of individual reservoirs between the plurality of individual ink reservoirs and a print head outlet, each ink regulator comprising: (i) a pressurized chamber including an ink inlet adapted to provide fluid communication with an ink source, an ink outlet adapted to provide fluid communication with a print head, and at least one exterior flexible wall having an inner surface facing an interior of the pressurized chamber; and, (ii) a lever including a flexible arm extending along a portion of the exterior flexible wall and an opposing arm operatively coupled to a seal, the seal closing the ink inlet when the lever is in a first position and to opening the ink inlet to allow fluid communication between the ink inlet and the pressurized chamber when the lever is pivoted to a second position, the lever being biased to the first position, where a higher pressure differential across the exterior flexible wall causes the exterior flexible wall to apply force against the flexible arm contacting the exterior flexible wall, overcoming the bias, to thereby pivot the lever to the second position, opening the ink inlet, where a lower pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall against the flexible arm contacting the exterior flexible wall to weaken, succumbing to the bias, which pivots the lever back to the first position, closing the ink inlet and, where a pressure change from the lower pressure differential to the higher pressure differential across the exterior flexible wall causes the force applied by the exterior flexible wall to increase and flex the flexible arm without overcoming the bias.
In a more detailed embodiment of the sixth aspect, the common wall is non linear. In another detailed embodiment, at least two of the plurality of individual reservoirs are separated by at least one common interior wall that is staggered. In still a further detailed embodiment, the ink cartridge is operatively coupled to a print head. In yet another detailed embodiment, at least one ink reservoir of the plurality of individual ink reservoirs of the ink cartridge is in fluid communication with a print head nozzle outlet.